Process of separating ferriferous zinc compounds.



UNITED sTATEs PATENT OFFICE.

GUY L. MEAKER, OF EVANSTON, ILLINOIS, ASSIGNOR TO THE AMERICAN STEEL &WIRE COMPANY OF NEW JERSEY, A CORPORATION OF NEW JERSEY.

PROCESS OF SEPARATING FERRIFEROUS ZINC COMPOUNDS.

Specification of Letters Patent.

Patented Sept. 19, 1905.

Application filed February 1,1905. Serial No, 243,660.

To all who/1'1, it may concern: I

Be it known that I, GUY L. MEAKER, acitizen of the United States,residing at Evanston, county of Cook, State of Illinois, have'inventedcertain new and useful Improvements in Processes of SeparatingFerriferous. Zinc Compounds, of which the following is aspecification.

My invention relates to a process for separating metallic zinc fromcompounds containing zinc in association with iron, such, for example,as the dross and skimmings from galvanizing-tanks in which zinc and ironare the principal elements. The same process is applicable to otherferriferous compounds of zinc, even when small amounts of other metals,such as lead and copper, are present.

My invention consists in dissolving the compound to be treated in anacid, such as hydrochloric or sulfuric, and then subjecting the solutionto electrolytic action in such manner that the metallic zinc isdeposited on the cathode, while the'iron is formed into an insolublebasic ferrous or ferric compound which appears as an ochreous powdersuspended in the electrolyte and which may be screened or filteredtherefrom at convenience or even left therein indefinitely, since byreason of its insolubility the iron in this form has no detrimentaleffect'on the deposition of the metallic zinc.

More particularly, I first dissolve the ferriferous compound in eithersulfuric or hydrochloric acid, whereby the Zinc is formed into either achlorid or sulfate of zinc and the iron,by the evolution of hydrogen, isconverted into the ferrous condition. It is then desirable that toelectrodeposit the metallic zinc from this solution some means must bedevised to prevent the simultaneous deposition of the iron or itsinterference in other ways with the electrolytic action on the zinc. Tothis end I have conceived of the plan of converting this iron from itsferrous condition into some other condition in which it will beinsoluble and consequently innocuous to the zinc deposition and at thesame time to accomplish this conversion by means germane to theelectrolyzing process itself.

The means I have devised are as follows: In the first place I have foundthat by establishing a certain ratio between the superficial area of theanode and cathode of the electrol lytic apparatus 1 may cause the ironto be changed from a ferrous to a ferric conditionthat is to say, ifthese two areas are the same there will be no change in the condition ofthe iron. If, however, the surface of the anode materially exceeds inarea the surface of the cathode the ferrous will be changed to a ferriccondition. On the other hand, if the area of the cathode exceeds that ofthe anode the iron is not only not oxidized from the ferrous to theferric condition, but any ferric iron is reduced. success under theconditions to be further described an anode having a superficialareaseven times as great as that of the cathode. In the second place,having brought the iron to the ferric condition I provide that it shalltake on oxygen, and thereby be converted into the basic condition-thatis, in the sense that the base is in excess-having the base atomicallygreater than that of the acid or the related neutral salt. To this end Ioxidize the solution, as by aeration, preferably causing it to circulatein a shallow receptacle with a considerable surface exposed to theatmosphere. In the event of the solution-being neutral on but slightlyacid the iron will pass directly from the ferrous to the basic ferrouscondition, the efliect on the main process remaining the same-namely,the elimination of the iron. In the third place, the proper performanceof the two operations aforesaid requires that instead of an anode ofzinc, serving both as a circuit-terminal and as a source of zinc formaintaining the solution, an insoluble anode, such as carbon, should beemployed. Moreover, the solution is constantly regenerated by retainingtherein after the electrolytic action takes. place the chlorin or otheractive agent and causing it to circulate through a regenerating-tank,where it passes through a mass of ferriferons zinc compound,

which is to be separated. From the regenerating tank or receptacle itpasses to the depositing electrolytic cell and then back to the saidtank, so that it circulates through the two in succession. In otherwords, the ferriferous compound itself may not be used as an anode, notonly because it is not ordinarily in a mechanical state permitting it tobe so used, but also because no definite size or character ofanode-surface can be maintained, nor a certain and adequatereplenishment of the In practice I have used with solution nor asufiiciently low and definite resistance. Upon these features thesuccess of my process is largely dependent, and I secure the resultsdesired by employing an anode of hard graphitic carbon, together withthe aforesaid external means of regeneration. In the fourth place,.it isrequired thata current density be employed greatly in excess of thedensity heretofore employed in any electrolytic process thatI am awareof. For example, in theHoepfner process of depositingzinc from thechlorid, a current density of one hundred amperes per square meter isemployed, or less than ten amperes per square foot of cathode-surface,while in the Szirinay process of galvanizing Wire by electrodepositionfrom metallic zinc adensity of ten amperes per square foot ofcathode-surface is employed. In my process I am now using about onethousand amperes per square foot of cathodesurface and do not expectthat in any event a densityof less than four hundred or five hundredwould be feasible. In the fifth place, it is important to thesatisfactory character of the deposited zinc that the cathode be kept inmotion. The precise reason for this I do now undertake to give, itapparently being independent of any washing or other effect produced bythe relative movement of the cathode with respect to the solution andalso independent of any intermittent exposure of the cathode to theatmosphere. The fact is as stated, however it may be explained. By thesemeans I am enabled to maintain a continuous process of deposition in athoroughly practical manner.

It is unnecessary to maintain any exact percentages of components in theelectrolytic solution or to measure them with care. The ferriferous zinccompounds may be shoveled into the regenerating-tank from time to timewith little regard to the precise amount, and acid may be added inalmost the same way. It is desirable that the solution should not fallbelow 16 Baum, but above that point the density of the solution has noapparent influence on the process, (save in the reduction of cost.)Moreover, I am enabled to work With dross, skimmings, and scrapmaterials, which have hitherto been waste products. I may also work fromroasted ores and similar materials, which it has heretofore beennecessary to refine into metallic zinc before subjecting them to anelectrolytic process. Finally, I am able to deposit the zinc with arapidity far beyond what has been heretofore considered possible and toany desired thickness. The deposition of zinc in the mossy, spongy, orblack-oxid form is Wholly eliminated, however rapidly or to whateverthickness the deposit is produced. I attribute the success of my processto the neutralization of the efiect of the iron in the manner described.As regards other metallic substances 1 rease which may be present in theferriferous compounds the lead will not enter into the solu tion in thedilute acids used of a strength less than one to four. As regardscopper, the amount to be found in these ferriferous zinc compounds is sosmall as to be negligible. Theoretically it would deposit along with thezinc, but I have been unable to detect its presence in any of the manyanalyses I have made of the deposited zinc.

What I claim as new, and desire to secure by Letters Patent, is-

1. In the process of separating ferriferous zinc compounds by renderingthe iron component neutral to the electrolytic action the method ofoxidizing the electrolytic solution which consists in giving the anodean active surface larger than that of the cathode.

2. The process of separating ferriferous zinc compounds which consistsin dissolving the compound to form an electrolytic solution, convertingthe iron into a neutral form by oxidizing means, including theproportioning of the electrode-surfaces so that the anode-surface shallsubstanially exceed that of the cathode, and electrodepositing the zincon the cathode. I

3. The process of separating ferriferous compounds of zinc, whichconsists in dissolving the compound into an electrolytic solution,

converting the iron from the ferrous to the ferric condition byproportioning the anode and cathode surfaces, converting it from theferric condition to an insoluble basic ferric condition by oxidation andelectrodepositing the zinc on the cathode.

4:. The process of separating ferriferous compounds of zinc, whichconsists in dissolving the compound into an electrolytic solution,transferring the solution from the point of formation to an anode ofinsoluble material adjacent to a cathode of smaller superficial area,passing an electric current from the anode to the cathode through thesolution, and oxidizing the solution, whereby the zinc is deposited onthe cathode and the iron is precipitated in an insoluble, basic, ferrousor ferric form.

5. The process of separating the iron from a ferriferous metalliccompound which consists in dissolving the compound into an electrolyticsolution, precipitating the iron in an insoluble form by passing anelectric current through said solution from an anode to a cathode ofsmaller superficial area and by oxidizing the solution andsimultaneously depositing the metal on the cathode.

6. The process of separating the iron from a ferriferous metalliccompound which consists in dissolving the compound into an electrolyticsolution, passing an electric current through said solution from ananode of insoluble material to a moving cathode of smaller superficialarea, and oxidizing the solution,

whereby the iron is precipitated in an insoluble form and the metal iselectrodeposited on the cathode.

7. Acontinuous process of separatinga ferriferous zinc compound whichconsists in circulating an acid solution through a receptacle containingthe compound to be separated and through an electrolytic cell insuccession, passing an electric current through the solution in saidcell from an insoluble anode to a cathode of smaller superficial areaand oxidizing the solution, whereby the iron is precipitated into thesolution in an insoluble form and the zinc is electrodeposited on thecathode.

8. The process of electrodepositing zinc from a ferriferous compoundthereof, which consists in dissolving the compound into an movingcathode by an electric current having a a density of atleast fourhundred amperes per square foot of cathode-surface.

In witness whereof I have hereunto set my hand, before two subscribingwitnesses, this 14th day of January, 1905.

GUY L. MEAKER.

Witnesses:

J. W. MEAKER, J12,

G. A. MASON.

